31.10.4 Commands to Add to the Diary

While in the calendar, there are several commands to create diary
entries. The basic commands are listed here; more sophisticated
commands are in the next section (see Special Diary Entries).
Entries can also be based on non-Gregorian calendars.
See Non-Gregorian Diary.

i d

Add a diary entry for the selected date (diary-insert-entry).

i w

Add a diary entry for the selected day of the week (diary-insert-weekly-entry).

i m

Add a diary entry for the selected day of the month (diary-insert-monthly-entry).

i y

Add a diary entry for the selected day of the year (diary-insert-yearly-entry).

You can make a diary entry for a specific date by selecting that date
in the calendar window and typing the i d command. This command
displays the end of your diary file in another window and inserts the
date; you can then type the rest of the diary entry.

If you want to make a diary entry that applies to a specific day of
the week, select that day of the week (any occurrence will do) and type
i w. This inserts the day-of-week as a generic date; you can then
type the rest of the diary entry. You can make a monthly diary entry in
the same fashion: select the day of the month, use the i m
command, and type the rest of the entry. Similarly, you can insert a
yearly diary entry with the i y command.

All of the above commands make marking diary entries by default. To
make a nonmarking diary entry, give a prefix argument to the command.
For example, C-u i w makes a nonmarking weekly diary entry.

When you modify the diary file, be sure to save the file before
exiting Emacs. Saving the diary file after using any of the above
insertion commands will automatically update the diary marks in the
calendar window, if appropriate. You can use the command
calendar-redraw to force an update at any time.